With each advancement of science, our knowledge of this world and the worlds outside it is increasing by leaps and bounds. Today we take much scientific knowledge for granted. But actually, they are the results of centuries of interpretations and experiments. For a long time common people, physicians, and even scientists based their theories more on beliefs rather than on scientific proofs. Those theories might make us laugh today, but at one time they were an integral part of people’s life. Keep reading this list to discover 10 crazy things scientists used to believe in.

1 Prior to the germ theory of disease, doctors believed the “miasma” theory according to which disease was spread through poisonous air rising up from the ground as a result of decaying organic matter carried by wind from stagnant swamps and cemeteries.

For many centuries, doctors and scientists debated over the possible cause of diseases such as chlamydia, cholera. or the black death. One of the most widely accepted theories in those times was the “miasma” theory. According to this theory, these epidemics were caused by miasma, i.e., bad air, emanating from rotting organic matter.

Since the ancient times, the miasma theory was accepted in Europe, China, and Southeast Asia. Miasma, the poisonous vapor or mist, was thought to be filled with particles from decomposed matter. During the 1850s, the miasma theory was challenged by physicians such as John Snow and Filippo Pacini. The definitive end of this theory came after 1876 when Robert Koch proved that the bacterium Bacillus anthracis caused anthrax, and then the germ theory started gaining a foothold. (1,2,3)

2 Before the widespread acceptance of the theory of plate tectonics, scientists believed that there existed large, prehistoric, intercontinental “land bridges” spanning thousands of miles of deep ocean.

At the present time, geologists and scientists all over the world agree to the fact that the surface of Earth is not a single, solid mass. It is rather made up of many plates that are residing and sliding on top of Earth’s mantle. But before the theory of plate tectonics came into existence, it was thought that the continents were joined through land bridges which are now submerged under water.

The theory of land bridges was formed when geologists noticed that some fossils and geological features of one continent matched with those of another even though both are separated by great oceans. They found fossils of many similar organisms and terrestrial plants in two or more continents. To explain such similarities, the orthodox science at that time put forward the theory that a long time ago land bridges, now sunken, connected these far-flung continents together. (1, 2)

3 Prior to 1860s, doctors did not wash their hands before attending to patients, and the doctor that proposed medical professionals should wash their hands before handling patients was so mocked by his peers that he suffered from a nervous breakdown.

In 1865, a Hungarian physician, Ignaz Philipp Semmelweis, was committed to an asylum as he suffered a nervous breakdown. The reason: he suggested that doctors should wash their hands after examining a patient. In those times, the germ theory of disease was not widely accepted. Hence, doctors didn’t wash their hands after performing an autopsy and even after examining a patient. The bed linens and laboratory coats were not washed. Surgical instruments were cleaned only when they were put away for storage.

Also, in those times, it was a common notion that a gentleman’s hands are always clean. Since doctors were gentlemen, they refrained from washing their hands. So, when Semmelweis suggested that doctors should wash their hands, he was mocked and ridiculed. After his death, the germ theory came into existence, and by 1875, scrubbing of hands and sterilization of instruments were widely practiced. (1,2)

4 Mercury was once considered safe and used as a disinfectant, laxative, cure for syphilis, and even as a pill for immortality.

Today, we are well aware that mercury is extremely toxic and a harmful, environmental pollutant. But in earlier times, common people, as well as scientists and physicians, used this “liquid silver” extensively. They believed it to be a miraculous substance capable of eradicating most diseases. Its popularity can be understood by the fact that when in 210 BC a Chinese emperor, Qin Shi Huang Di, wanted to become immortal, he was given potion or pills containing mercury by his court scientist. It ultimately led to his death.

In the sixteenth century, mercury was extensively used in medicine. For the next four centuries, mercuric compounds were an essential ingredient in drugs in both Asian and European pharmacopeias. As a result, more people died of mercury poisoning than from the maladies they were actually suffering. Even in the 1990s, mercury was used as a spermicide. It is still used in dental amalgams, cosmetics, saline solutions, and eye drops. (1,2,3,4)

5 Before the invention of railways, it was believed that people would suffocate if they traveled faster than 30 mph as they would not be able to breathe due to the surrounding air rushing past them.

Can you imagine a world without trains? Probably not. It is one of the cheapest and extensively used modes of land transportation. But before the invention of railways, people had very negative and rather funny notions about anything that travels faster than 30 mph. A train journey was believed to be harmful to the brain. It was believed that the jarring motion of train could drive a normal person insane and the noise could shatter nerves.

During the 1860s and ’70s, many cases of “railway madmen” were reported. The media took up the topic, and bizarre behavior of passengers on trains became common news. Physicians and psychologists wrote extensively about this topic. Even medical journals contained articles that contained information as to how railway madmen can be detected. Eventually, the railway-madmen hype ran out and the problem faded out as inexplicably as it had appeared. (1, 2)